Pacemakers, defibrillators and implanted cardioverter defibrillators (“ICDs”) have been successfully implanted for years for treatment of heart rhythm conditions.
Pacemakers are implanted in patients who have bradycardia (slow heart rate). The pacemakers detect periods of bradycardia and deliver electrical stimuli to increase the heartbeat to an appropriate rate.
ICDs are implanted in patients who may suffer from episodes of fast and irregular heart rhythms called tachyarrhythmias. An ICD can cardiovert the heart by delivering electrical current directly to the heart to terminate an atrial or ventricular tachyarrhythmia, other than ventricular fibrillation. An ICD may alternatively defibrillate the heart in a patient who may suffer ventricular fibrillation (VF), a fast and irregular heart rhythm in the ventricles. During a VF episode, the heart quivers and can pump little or no blood to the body, potentially causing sudden death. An ICD implanted for correction of ventricular fibrillation will detect a VF episode and deliver an electrical shock to the heart to restore the heart's electrical coordination.
Another type of implantable defibrillation device treats patients who may suffer from atrial fibrillation (AF), which is a loss of electrical coordination in the heart's upper chambers (atria). During AF, blood in the atria may pool and clot, placing the patient at risk for stroke. An electrophysiological device implanted for correction of atrial fibrillation will detect an AF episode and deliver an electrical shock to the atria to restore electrical coordination.
Pacemakers and ICDs are routinely implanted in the pectoral region either under the skin (subcutaneous) or under the pectoral muscle. The leads are placed at appropriate locations around, within or on the heart. Because of this complexity, a cardiologist identifying a heart rhythm condition may be required to refer his or her patient to sub-specialists or surgeons for implantation of a pacemaker or ICD—thus delaying implantation of the device in a patient who urgently needs it. It is thus desirable to simplify these devices and the procedures for implanting them so as to permit their implantation by a broader range of physicians.
U.S. application Ser. Nos. 10/453,971 and 10/454,223 (“the '971 and '223 applications), filed Jun. 4, 2003, and Ser. No. 10/862,113, filed Jun. 4, 2004 (the '113 application) describe intravascular systems that may be used to deliver electrical energy to the heart such as for defibrillation, pacing, and/or cardioversion of the heart. Each of these applications is incorporated herein by reference for all purposes.
Generally speaking, the systems described in the '971, '113 and '223 applications include at least one housing containing the necessary circuitry and related components for delivering a charge to the heart for pacing, and/or defibrillation, etc. The systems may also include at least one electrode lead through which the electrical energy is delivered to the body. Some or all of these components are positioned within the vasculature, such as in the superior vena cava (“SVC”), the inferior vena cava (“IVC”), or the left or right subclavian, coronary sinus, and/or other vessels of the venous or arterial systems. For example, the housing containing electronics, circuitry, batteries, capacitors, etc. may be positioned in the IVC or SVC, while leads extending from the housing may extend to the left subclavian vein (LSV), the IVC, the coronary sinus of the heart, and/or the right ventricle of the heart. Retention devices may be used to retain some of these components within the vasculature.
The present disclosure describes components that facilitate implantation and later removal of the housing containing electronics, circuitry, batteries, etc. in an intravascular system. In particular, the application describes a sleeve or “exoskeleton” that is implanted in the vasculature. The exoskeleton may be retained in place using a retention device. Following implantation of the exoskeleton, the housing is inserted into the exoskeleton. If at some date it becomes necessary to explant the housing, it may be withdrawn from the exoskeleton and removed from the body, leaving the exoskeleton in place.